P0055 HO2S Heater Resistance Bank 1 Sensor 3

P0055 indicates heater resistance outside expected limits for bank 1 sensor 3. The third oxygen sensor heater on bank 1 is electrically abnormal.

Code details

Generic OBD-II · P0

System: Fuel / Air
Code type: Generic (SAE / ISO controlled)
Standard: SAE J2012 / ISO 15031-6

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not repair the wrong oxygen sensor position; confirm bank 1 sensor 3 before testing or replacement.

Symptoms of P0055

Check-engine light on, sometimes with rough or uneven running.
Hesitation, surging, or a noticeable change in fuel economy.
Occasionally hard starting or a smell of unburnt fuel.

Common causes of P0055

A failing or contaminated sensor (MAF, MAP, oxygen or air-fuel sensor).
Intake or vacuum leaks, or an exhaust leak near an upstream sensor.
Wiring, connector, or fuel-delivery problems that skew the reading.

Useful checks before replacing parts

Measure bank 1 sensor 3 heater resistance, feed voltage, control circuit, ground, fuse supply, and loaded current draw.
Inspect the downstream sensor harness for exhaust heat damage, loose terminals, connector corrosion, and shared heater feed problems.
Verify sensor location and bank assignment before comparing warm-up behavior or replacing the sensor.

Related OBD-II codes

These nearby fuel / air entries can help compare wording and pin down the fault area.